Apparatus and method for facilitating the connection of tubulars using a top drive

ABSTRACT

An apparatus and method for facilitating the connection of tubulars using a top drive and is, more particularly but not exclusively, intended for facilitating the connection of a section or stand of casing to a string of casing.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/745,966, May 8, 2007; which is a continuation of U.S. patentapplication Ser. No. 10/831,864, filed Apr. 26, 2004, now U.S. Pat. No.7,213,656; which is a continuation of U.S. patent application Ser. No.09/868,790, now U.S. Pat. No. 6,725,938, which is the National Stage ofInternational Application No. PCT/GB99/03951, filed on Nov. 29, 1999,and published under PCT Article 21(2) in English, which claims priorityof United Kingdom Application Serial No. GB9828673.5, filed on Dec. 24,1998. Each of the aforementioned applications is incorporated herein byreference in their entirety.

BACKGROUND OF THE INVENTION

This invention relates to an apparatus and method for facilitating theconnection of tubulars using a top drive and is, more particularly butnot exclusively, intended for facilitating the connection of a sectionor stand of casing to a string of casing.

SUMMARY OF THE INVENTION

In the construction of oil or gas wells it is usually necessary to linethe borehole with a string of tubulars known as casing. Because of thelength of the casing required, sections or stands of say two or threesections of casing are progressively added to the string as it islowered into the well from a drilling platform. In particular, when itis desired to add a section or stand of casing the string is usuallyrestrained from falling into the well by applying the slips of a spiderlocated in the floor of the drilling platform. The new section or standof casing is then moved from a rack to the well centre above the spider.The threaded pin of the section or stand of casing to be connected isthen located over the threaded box of the casing in the well and theconnection is made up by rotation therebetween. An elevator is thenconnected to the top of the new section or stand and the whole casingstring lifted slightly to enable the slips of the spider to be released.The whole casing string is then lowered until the top of the section isadjacent the spider whereupon the slips of the spider are re-applied,the elevator disconnected and the process repeated.

It is common practice to use a power tong to torque the connection up toa predetermined torque in order to make the connection. The power tongis located on the platform, either on rails, or hung from a derrick on achain. However, it has recently been proposed to use a top drive formaking such connection.

Because of the high costs associated with the construction of oil andgas wells time is critical and it has been observed by the applicantsthat the time to connect a tubular to a top drive using existingequipment could be reduced.

It has been observed that sections or stands of tubulars are often notas uniform as desired. In particular, the sections or stands of tubularsare often not straight. The top drive is in perfect alignment with thecentre of the spider in the platform of an oil or gas rig. However, asection or stand of tubulars located in the spider would not always bein alignment with the top drive.

There is described an apparatus and method for facilitating theconnection of tubulars using a top drive in co-pending UK PatentApplication No. 98 18363.5, which apparatus comprises a statorattachable to the top drive and a supporting member for supporting atool wherein means are provided to allow substantially horizontalmovement of said supporting member.

The apparatus disclosed therein is bulky, cumbersome and awkward to use.The present invention attempts to reduce these problems.

Accordingly, there is provided an apparatus for facilitating theconnection of tubulars using a top drive, the apparatus comprising asupporting member for connection with said top drive, a tool forgripping a tubular and means for allowing substantially horizontalmovement therebetween wherein said means comprises a flexible membraneenclosing a fluid.

Other features of the invention are set out in claims 2 to 15.

There is also provided a method for facilitating the connection oftubulars, the method comprising the steps of moving a tool for grippinga tubular substantially in a horizontal plane relative to a supportingmember whereupon a flexible membrane located therebetween is deformed.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, reference will nowbe made, by way of example, to the accompanying drawings, in which:

FIG. 1 is a view in perspective of an apparatus according to theinvention the apparatus being shown in use;

FIG. 2 is a front plan view of the apparatus of FIG. 1, the apparatusbeing shown in use;

FIG. 3 is an enlarged cross-sectional view of parts of FIG. 1.

DETAILED DESCRIPTION

Referring to the drawings, there is shown an apparatus for facilitatingthe connection of tubulars using a top drive. The apparatus is generallyidentified by reference numeral 1.

The apparatus 1 is shown connected to a rotor 2 of a top drive 3 viaconnection 4 to a rotor 5 of the apparatus 1. The top drive 3 is locatedon rails on a derrick of a rig (not shown). A rigid member 6 is fastwith a static part of the top drive 3. The rigid member surrounds therotor 5. The rigid member 6 has a clamp therein which, when required,applies jaws (not shown) to the rotor 5 such that, upon rotation of therotor 2 of the top drive 3, the apparatus 1 may be connected ordisconnected from the top drive 3. When the jaws are released, the rotor5 may rotate freely within the rigid member 6.

The apparatus 1 is shown with a stand of casing 7 inserted therein. Anelevator 8 is shown gripping the stand of casing 7 with the use ofgripping elements 9. The elevator 8 is suspended from the top drive 3 onbails 10 and 11. The stand of casing 7 is guided by a pipe handling arm12.

The apparatus 1 comprises a housing 13 which depends from the rotor 5via a supporting element 14 and three piston and cylinders 15. The threepiston and cylinders 15 allow small vertical movements of the apparatus1 relative to the top drive 3. The three pistons and cylinders 15 may behydraulically activated or pneumatically activated or using acombination of both pneumatic and hydraulic fluids.

The housing 13 accommodates a hub 16 which is radially and rotationallymoveable therein. The hub 16 has a circumferential recess 17 into whichan inflatable ring 18 is arranged. The inflatable ring 18 is infrictional engagement with both the hub 16 and an internal wall 19 ofthe housing 13. The hub 16 has a central bore 20 into which one end of amud pipe 21 is inserted. The mud pipe 21 is provided for carrying mud tothe inside of the tubular 7. The mud pipe 21 is mounted in cylindricalsections 22 and 23 which are attached to the hub 16 and the supportingelement 14 respectively. The mud pipe 21 is provided with a lobe 24formed on the outer surface thereof and is located in a correspondingrecess 25 in the cylindrical section 22. A lobe 26 is slidably arrangedon the upper end of the mud pipe 21 with an o-ring seal 27 arrangedtherebetween to inhibit fluid from leaking therebetween. The lobe 26 islocated in a corresponding recess 28 in the cylindrical section 23. Thisarrangement allows a ball and socket type movement between thesupporting element 14 and the hub 16 and relative longitudinal movementtherebetween. The upper end of the mud pipe 21 is allowed to move freelyin a spherical recess 29 in the supporting element 14.

A circulating tool generally identified by reference numeral 30 is fixedto and depends from the hub 16. The circulating tool 30 comprises acylindrical body 31 which has a central passage 32 therethrough. Thecylindrical body 31 has a plurality of recesses 33 thereabout in whichgripping elements 34 are located. The gripping elements 34 are providedwith recesses 35.

The cylindrical body 31 is also provided with an inflatable sealing ring36 arranged below the gripping elements 34.

The cylindrical body 31 is provided with a feed passage 37 the upper endof which is connected to a hydraulic fluid supply and at the other endto the recesses 35 in the gripping elements 34. A feed passage 38connects the inflatable sealing ring 36 with the inside of the tubular7.

A clamping device 39 depends from the housing 13 on a rigid cylinder 40.The clamping device 39 comprises two rigid plates 41 and 42 betweenwhich is arranged three hydraulic pistons 43 spaced at 1200 to eachother. The hydraulic pistons 43 are provided with gripping elements 44for engaging with the tubular 7.

In use, the apparatus I is fitted to the rotor 2 of a top drive 3 viathe rotor 5 of the apparatus 1. When it is desired to connect a stand oftubulars such as casing to a string of casing already lowered into awellbore and suspended from a spider in the rig floor (not shown), thefollowing steps are performed.

A stand of casing is moved from a storage area to the well centre, andis gripped by the pipe handling arm 12. The pipe handling arm 12, ifnecessary, moves the stand of casing to a position where the apparatus 1may be lowered onto the top of the stand of casing. The apparatus 1 islowered with the top drive 3 on the rails on the derrick of the rig. Asthe apparatus 1 is lowered, the circulating tool 30 inserts itselfinside the stand of casing and the clamping device 39 passes over thebox 45 of the casing 7.

The gripping elements 34 are moved radially outwardly by the hydraulicfluid pressure build up through feed passage 37 and into recess 35. Thegripping elements engage with the internal wall of the casing 7. Itshould be noted that the weight of the stand of casing may now be takenby the gripping elements 34. The pipe handling arm 12 can now move thestand of casing into exact alignment with the box of the casing stringprotruding above the spider in the rig floor. This step is necessary dueto the stands of casing being slightly bent. As the stand of casing 7moves, the circulating tool 30 moves with the casing 7. The pneumaticfluid in the inflatable ring 18 allows relative movement between thestationary top drive 3 and circulating tool and hence the casing 7. Oncealigned, the stand of casing is lowered (“stabbed”) into the box of thecasing string by activation of piston and cylinders 15. Low torquerotation of the stand of casing now begins by rotation of the top driverotor 2. It should be noted that the inflatable ring 18 helpsaccommodate non-linearity in the casing 7 since it allows the top of thecasing 7 to float with respect to the longitudinal axis of the top drive3 whilst being rotated to engage the pin of the casing 7 in the box ofthe casing string held in the spider in the rig floor. The low torque istransferred from the rotor 2 of the top drive through the piston andcylinders 15, through the housing 13 and via the inflatable ring 18 tothe circulating tool 30 and hence to the stand of casing 7 via thegripping elements 34. The threaded pin of the stand of casing 7 is nowpartially made up with the threaded box of the casing string. The pipehandling arm 12 may now be removed from the casing 7 and swung into aninoperative position. The three piston and cylinders 43 of the clampingdevice are now activated evenly which moves the top of the stand ofcasing 7 and the circulating tool 30 into exact alignment with the topdrive. The top drive may now be used to complete make-up by rotating thestand of casing typically up to 95,000 Nm (70,000 lb/ft) of torque. Thehigh torque is transferred from the top drive 3 through piston andcylinders 15 through the housing 13, the rigid cylinder 40 and theclamping device 39 and hence to the stand of casing 7.

The spider may be used to hold the casing string 7 against rotationwhile this operation is carried out.

The elevator B may now be swung around the top of the casing 7.Circulation may now take place. Any pressure build up in the casing 7would force the inflatable sealing ring 36 out and into engagement withthe casing wall due to pressure build up through the feed passage 38.Circulating fluid may be pumped in to the casing string through mud pipe19, central bore 20 and central passage 32.

The spider may be released allowing the elevator 8 to take the weight ofthe casing string. The elevator 8 may lower the casing string into thewellbore. During lowering the top drive 3 may continue to rotate theapparatus 1 and hence rotate the casing string at up to 95,000 Nm(70,000 lbs/ft) of torque, if required.

The apparatus 1 may be removed by deactivating the piston and cylinders43 of the clamping device 39, the gripping elements 34 of thecirculating tool 30, deflating the inflatable sealing ring 36 andlifting the apparatus 1 by raising the top drive 3.

A reverse sequence may be used to disconnect stands or single pieces ofcasing from a casing string.

It is envisaged that various modifications or variations may be made tothe above described embodiment. In particular, the inflatable ring 18may contain pneumatic fluid and be sealed. Alternatively, the inflatablering 18 may be provided with a pneumatic supply line for controlling thepressure of the pneumatic fluid therein, for example for lowering thepressure when aligning the casing. The inflatable ring 18 may containhydraulic fluid and be provided with a waste gate or a supply line forcontrolling the quantity of hydraulic fluid therein. A combination ofboth hydraulic and pneumatic fluids may be used preferably usinghydraulic fluid in the inflatable ring and pneumatic bellows.

The inflatable ring may be a vehicle tyre.

It is envisaged that in certain embodiments the apparatus 1 may not bedirectly linked to the top drive 3. In particular, a motor,advantageously a hydraulic motor, may be inserted between the top drive3 and the apparatus 1 for providing accurate speed of rotation andcontrol for making up the casing.

It is envisaged that the apparatus 1 could be used for rotating thecasing while lowering the casing. Reciprocation of the casing may alsobe provided simultaneously by raising and lowering the elevator.

It is envisaged that the casing string may be provided with a drillingbit as its lower end. The apparatus 1 may be used, with the clampingdevice 39 actuated, to rotate the casing and hence the drill bit, fordrilling a wellbore.

It is conceivable that the clamping device 39 could be dispensed withand the entire torque from the top drive transmitted through theinflatable ring 18, particularly if highly pressurized with hydraulicfluid at the time it is desired to transmit high torque.

It is also envisaged that any suitable mechanism and method of actuationcould be used for external clamping. For example, the mechanism couldcomprise cam surfaces with rough material thereon. The method ofactuation could be mechanical, electrical, pneumatic, hydraulic orchemical. A design from a power tong may be suitable for this purpose.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A method of connecting a first casing to a second casing using a topdrive, comprising: coupling a gripping apparatus to the top drive, thegripping apparatus having a gripping element adapted to engage the firstcasing; actuating the gripping element to engage the first casing; andactuating the top drive to rotate the gripping apparatus and the firstcasing relative to the second casing thereby connecting the first casingto the second casing.